Dispersions comprising an oil-based biliquid foam and an aqueous gel

ABSTRACT

PCT No. PCT/GB97/00608 Sec. 371 Date Sep. 4, 1998 Sec. 102(e) Date Sep. 4, 1998 PCT Filed Mar. 6, 1997 PCT Pub. No. WO97/32559 PCT Pub. Date Sep. 12, 1997A stable dispersion comprising an oil-based biliquid foam and an aqueous gel which is suitable for use in the cosmetics, pharmaceuticals and other industries. The biliquid foam comprises a dispersion of oil droplets in an aqueous medium stabilized by only a small amount of surfactant, thus keeping the level of skin irritation low. The gel may be a colloidal aqueous gel.

BACKGROUND OF THE INVENTION

This invention relates to new dispersions, and more particularly itrelates to stable dispersions of water-insoluble substances in aqueousmedia which are based on biliquid foams entrapped in aqueous gels.

Dispersions of oils and oil-soluble materials in aqueous media arewidely used in many industries, in particular the cosmetics, food,paints, pharmaceuticals and printing industries. Such dispersionstypically depend for their stability on the presence of surface-activechemicals, generally known as emulsifying agents or surfactants, whichmigrate to the oil-water interface which surrounds each individualsuspended oil droplet, and prevent said droplet from coalescing withother droplets with which it may come into contact. Such dispersions aregenerally known as emulsions and typically contain, depending on thechemical nature and concentration of the components of the emulsion,from 3 to 10% by weight of surfactant.

A disadvantage of the presence of surfactants in emulsions, particularlyin the cosmetics and pharmaceuticals industries, is their potential, toa greater or lesser extent, to cause skin irritation. This arises fromthe physico-chemical nature of all surfactant molecules, especially fromtheir ability to combine with skin lipids, and isconcentration-dependent. It is therefore essential, in well-formulatedcosmetic and pharmaceutical products, to use the minimum surfactantconcentration consistent with providing stability of the emulsion, butsaid minimum concentration in practical terms is necessarily fairlyhigh.

A further disadvantage of the presence of surfactants in emulsions istheir detrimental effect on the efficacy of many preservatives, whichare essential in emulsion formulations to prevent the growth of unwantedorganisms such as bacteria, yeasts and other fungi. As a result, in thepresence of surfactants, levels of preservatives need to be higher thanthey might otherwise be. The disadvantage is compounded because thepreservatives themselves are skin-sensitizing, and higher levels thereofexacerbate the skin problems.

Apart from the problem with surfactants, many emulsions known for use ascosmetics or pharmaceuticals contain, in order to produce stableformulations of desired viscosity, fatty chemicals such as cetyl orstearyl alcohol, glyceryl stearate, petroleum, or waxes, either natural(for example beeswax, candelilla wax or carnauba wax) or synthetic (suchas microcrystalline or paraffin wax). These form a fatty, pore-clogging,occlusive film on skin which users find abhorrent.

By virtue of the oily materials which they contain, many emulsions,particularly those used as skin cleansers, have to be removed from theskin by wiping with tissue material, and cannot be rinsed from the skinby aqueous means and remain effective, and these emulsions are not likedby their users for this reason.

An alternative cosmetic or pharmaceutical product for topical usecomprises a liquid or gel wherein the gelling agent is either entirelywater-based, or alternatively entirely oil-based. The disadvantage ofthe former type is that, despite feeling light and refreshing in use, itcannot deliver oil-soluble or oil-dispersible materials to the skin, andthe disadvantage of the latter type is the unpleasantness in use, asexplained in the previous paragraph.

There are also known aqueous gel products designed for cleaning andconditioning hair and skin, which comprise high levels of surfactants,either with or without additional gelling agents. Such products areknown as hair shampoos, body shampoos, bath or foam gels, bubble or foambaths and products of similar descriptions. The primary purpose of suchproducts is as hair or skin cleansers, but a secondary objective is toprovide a lasting pleasant feel to the hair or skin, and to provide alustrous shine to the hair, these effects being generally known as"conditioning". Oils used in skin care products, particularly siliconesand their derivatives, are amongst the most effective conditioningagents but it is difficult to incorporate these into shampoos andsimilar products in sufficient quantities to provide an adequateconditioning effect, without destroying gel viscosity or foaming effect.

Dispersions of oil droplets in aqueous media are known which arestabilized by thin films containing low levels of surfactants, and thesefilms are generally known as "biliquid foams". These foams are notemulsions (Sebba, Chemistry and Industry, 1984, pp 367-372) and maycontain dispersed oil content of up to 95% by volume. They areinsufficiently stable to form useable cosmetic or pharmaceuticalproducts because the foam breaks at the air-water interface and depositsa layer of oil on the surface which, for reasons set out above, isunacceptable to the user.

The present invention is addressed to formulations for use in thecosmetics, pharmaceuticals and other industries which are based onbiliquid foams, but which do not possess the disadvantages set out aboveand in particular are less skin-irritant by virtue of their requirementfor only low levels of surfactants, and as a consequence only low levelsof preservatives.

SUMMARY OF THE INVENTION

The invention comprises a stable dispersion comprising an oil-basedbiliquid foam an d an aqueous gel which may be a colloidal aqueous gel.

The oil-based biliquid foam will generally comprise betweenapproximately 1 and 80%, preferably 1 and 50%, by weight of the totalformulation, and the aqueous gel will comprise between approximately 20and 99%, preferably 50 and 99% thereof. A surfactant to stabilize theformulation may comprise between 0.05 and 0.5%, and preferably between0.05 and 0.3%, thereof. The active ingredient if there is such can bepresent in either the aqueous phase or the oily phase.

Oils used in the biliquid foam will in general be liquid at roomtemperature and may be, for example, a cyclomethicone, dimethicone,dimethiconol, dimethicone copolyol, an emollient ester such as isopropylisostearate, lanolate, myristate or paimitate, or octyl palmitate, aglyceride such as avocado oil, coconut oil, soybean oil or sunfloweroil, or a caprelic/capric triglyceride, a lanolin oil, mineral oil ornatural oil, or olepl alcohol, or any other oil generally known for thispurpose.

DETAILED DISCLOSURE

The aqueous phase will in general comprise a colloidal polymer or gumsuspended in water, at a concentration of between 0.05 and 20%, moreparticularly 0.2 to 1%, by weight. Suitable polymers or gums are, forexample, alginate gums or their salts, guar gum, locust bean gum,xanthane gum, gum acacia, gelatin, hydroxymethylcellulose or its sodiumsalt, hydroxyethyl-cellulose, hydroxypropylcellulose,carboxymethylcellulose, bentonites, magnesium aluminum silicates,"Carbomers" (salts of cross-linked polymers of acrylic acid), orglyceryl polymethacrylates or their dispersions in glycols, or anyappropriate mixture of any of these polymers and gums. Preferred gellingagents are those which confer plastic behaviour on the aqueous phase,that is, under their influence, any shear stress applied to the productmust attain a minimum yield value before any liquid flow takes place.

The aqueous phase may also contain water-soluble or water-dispersiblematerials commonly used in cosmetic or pharmaceutical formulations, suchas an alcohol (for example ethanol or propanol), a glycol (for examplepropylene glycol), glycerin, an aqueous or alcoholic extract of anatural plant, a conditioning agent, a humectant or any otherwater-soluble material generally known for this purpose.

The formulation may contain, as described above, a low level of asurfactant which may be, for example:

a cationic surfactant such as an amidoamine, a quaternary ammoniumcompound or

a sulphonium salt;

an amphoteric surfactant such as an acylaminoacid, an N-substitutedalkylamine, an N-alkyl-β-aminopropionate, an N-alkylbetaine, analkylimidazoline or a sulphobetaine;

an anionic surfactant such as an acyl-lactate, N-acylsarcosinate,alkyl-carboxylate (either mono- or polyvalent), alkyl ether carboxylate,N-alkyl-glutamate, fatty acid-peptide condensate, phosphated ethoxylatedalcohol,

alkyl sulphate, ethoxylated alkyl sulphate, alpha-olefin sulphonate orester-linked sulphonate;

a nonionic surfactant such as an alkanolamide, amine oxide, ester of apolyhydric alcohol (for example an ester of an ethylene, diethylene orpropylene glycol, or glycerol or a polyglycerol, or sorbitan, glucose orsucrose), a polyoxyethylene or polyoxypropylene derivative of analcohol, amide or ester, or a polyoxyethylene/polyoxypropylene blockcopolymer; or a suitable compatible mixture of these surfactants.

The formulation may also contain an antimicrobial agent (preservative)such as an ester of p-hydroxybenzoic acid, formalin orimidazolidinylurea, or any other such product generally known for use inthe cosmetics or pharmaceutical industries. It may further contain anopacifying or pearlising agent, for example an alkanolamide of a higherfatty acid such as stearic or behenic acid, a glycol mono- or distearateor palmitate, a propyleneglycol monostearate or palmitate, a fattyalcohol such as cetyl or stearyl alcohol, an emulsion of a vinyl polymeror latex, an insoluble salt, such as a calcium, magnesium or zinc salt,of stearic acid, finely dispersed zinc and/or titanium oxide, a titaniumcoated mica, magnesium aluminum silicate or any other such productgenerally known for use in the cosmetics or pharmaceutical industries.It may still further contain an antioxidant, a sequestering agent, suchas ethylenediamine tetraacetic acid (EDTA) or a salt or polyphosphatethereof, a colouring agent (for example an acceptable dye or pigment),flavouring agent or perfume, or any other such agent generally known foruse in these industries.

One advantage of the formulation of the present invention over those ofthe prior art is that it can deliver oil-soluble products to the skinwithout giving rise to the unacceptable layer of oil formed, asexplained above, by the prior art formulations. A second advantage isthat the formulation of the present invention may be rinsed from theskin by aqueous means and still remain effective.

According to a further Feature of the invention there is provided acleansing and conditioning formulation which comprises a conventionalhair or skin cleansing formulation to which is added a biliquid foam.

A suitable conventional hair or skin cleansing formulation is, forexample, a hair or body shampoo or a bath or shower gel which willgenerally consist of an aqueous fluid containing between 4 and 18% byweight of a primary surfactant (for example an alkyl ether sulphate),between 2 and 15% by weight of a coactive surfactant (for example analkyl betaine) and between 0.5 and 5% by weight of a coactive viscositymodifier (for example an alkyl fatty acid alkanolamide), andadditionally or alternatively containing between 0.05 and 5% of agelling agent, for example a cellulose gum, a "Carbomer" or a polyolfatty acid ester. Such a formulation may also contain one or moreperfume, colouring agent, stabiliser (for example an antioxidant, asequestering agent or a UV-absorbing agent) and/or preservative. It isclear from the above description that by the nature of the conventionalformulations this kind of dispersion contains a higher proportion ofsurfactant than those previously described as features of the invention.

The biliquid foam will generally contain an oil-based conditioningagent, for example a mineral oil, an emollient fatty acid ester or asilicone oil or other silicone derivative. The biliquid foam willgenerally form between 0.5 and 10%, and more particularly between 2 and5%, of the total formulation. At such a concentration the conditioningproperties of the formulation will be enhanced but the foaming and gelviscosity characteristics of the formulation will be retained.

According to a further feature of the invention there is provided amethod for the manufacture of a dispersion of the invention whichcomprises incorporating an oil-based biliquid foam into an aqueous gel.Commonly the aqueous gel will be a conventional aqueous formulation ofthe appropriate type.

The invention is illustrated but not limited by the following Examples,in which all percentages are expressed by weight:

EXAMPLE 1

A skin-cleansing product

The aqueous phase consists of the following components:

    ______________________________________                                                                %                                                     ______________________________________                                        De-ionized water          95.54                                                 Propylene glycol 3.00                                                         Triethanolamine 0.80                                                          Cross-linked polymethacrylate (`Carbopol` 980, 0.50                           B F Goodrich)                                                                 Methylparaben 0.08                                                            Imidazolidinylurea (`Germall` 115, Sutton Labs.) 0.08                          100.00                                                                     ______________________________________                                    

The `Carbopol` was dispersed into the water using a high-shearrotor-stator mixer. The preservatives (methylparaben andimidazolidinylurea) were dissolved in the propylene glycol with gentlewarming and the solution was added to the aqueous dispersion. Thetriethanolamine was added until pH 6.5 was achieved and there was thusobtained a clear aqueous gel.

The biliquid foam consists of the following components:

    ______________________________________                                                               %                                                      ______________________________________                                        Light mineral oil        90.05                                                  De-ionised water 9.00                                                         Polyoxyethylene (3) lauryl ether (`Volpo` L3, Croda) 0.90                     Lauryl betaine (`Empigen` BB, Marchon) 0.05                                    100.00                                                                     ______________________________________                                    

Air was blown through a mixture of the lauryl betaine and the water toproduce a foam, and a mixture of the ethoxylated lauryl ether and themineral oil was added with gentle stirring. There was thus obtained abiliquid foam of which 30 g was added to 70 g of the aqueous gel toproduce a cleansing product. This product has the superficial appearanceof a cream but exhibits gel-like characteristics. It is mild andrefreshing upon application to the skin, is an effective skin-cleansingagent and may easily be removed from the skin either by wiping withtissue or rinsing with clear tepid water.

EXAMPLE 2

A Conditioning Shampoo

The total composition of the shampoo is as follows:

    ______________________________________                                                               %                                                      ______________________________________                                        33% Aqueous ammonium lauryl sulphate                                                                   41.0                                                   De-ionised water 29.8                                                         30% Aqueous ammonium lauryl ether sulphate 13.0                               30% Cocamidopropyl betaine 5.0                                                90% Dimethicone biliquid foam 3.5                                             Sodium chloride 3.0                                                           Ethylene glycol distearate 1.5                                                Citric acid 1.0                                                               Coconut diethanolamide 1.0                                                    Cetostearyl alcohol 0.5                                                       Fragrance 0.5                                                                 5-Bromo-5-nitro-1,3-dioxan in propylene glycol 0.2                            (`Bronidox L`, Henkel,), used as a preservative                               Colouring agent trace                                                          100.0                                                                      ______________________________________                                    

The biliquid foam was prepared as described in Example 1 except thatdimethicone (Silicone fluid 200/350, Dow Corning), was substituted forthe mineral oil. All the above ingredients apart from the fragrance,preservative and colouring agent were mixed together and heated to 70°until a clear viscous mass was formed. The mixture was then stirred andcooled to 40° and the fragrance and preservative were added. The mixturewas adjusted to pH 5.5 by the addition of extra citric acid, and to aviscosity of 9,000 centipoise by the addition of extra sodium chloride,and finally a suitable colouring agent was added. There was thusobtained a hair shampoo which was pearly opaque, deeply foaming and leftthe hair shiny, manageable and feeling well-conditioned.

EXAMPLE 3

A Conditioning Shampoo

The total composition of the shampoo is as follows:

    ______________________________________                                                                %                                                     ______________________________________                                        33% Aqueous ammonium lauryl sulphate                                                                    41.0                                                  De-ionised water 20.8                                                         30% Aqueous ammonium lauryl ether sulphate 13.0                               30% Cocamidopropyl betaine 5.0                                                90% Dimethicone biliquid foam 3.5                                             Cross-linked polymethacrylate (1% `Carbopol` 980, 10.0                        B F Goodrich, neutralised with triethanolamine)                               Sodium chloride 3.0                                                           Ethylene glycol distearate 1.5                                                Coconut diethanolamide 1.0                                                    Cetostearyl alcohol 0.5                                                       Fragrance 0.5                                                                 5-Bromo-5-nitro-1,3-dioxan in propylene glycol 0.2                            (`Bronidox L`, Henkel,), used as a preservative                               Colouring agent trace                                                          100.0                                                                      ______________________________________                                    

The biliquid foam was prepared as described in Example 1 except thatdimethicone (Silicone fluid 200/350, Dow Corning), was substituted forthe mineral oil. All the above ingredients apart from the fragrance,preservative and colouring agent were mixed together and heated to 70°until a clear viscous mass was formed. The mixture was then stirred andcooled to 40° and the fragrance and preservative were added. The mixturewas then stirred and adjusted to pH 6.5 by the addition of citric acid,and to a viscosity of 9,000 centipoise by the addition of extra sodiumchloride, and finally a suitable colouring agent was added. There wasthus obtained a hair shampoo which was pearly opaque, deeply foaming andleft the hair shiny, manageable and feeling well-conditioned.

EXAMPLE 4

A Moisturiser

The total composition of the moisturiser is as follows:

    ______________________________________                                                                  %                                                   ______________________________________                                        Water                       31.8                                                Cross-linked polymethacrylate (1% `Carbopol` 980, 37.0                        B F Goodrich, neutralised with sodium hydroxide)                              2% Aqueous hydroxyethylcellulose (`Natrosol` 250HR, 18.5                      Aqualon)                                                                      90% Mineral oil biliquid foam 1.6                                             90% Cyclomethicone biliquid foam 3.5                                          90% Isopropyl isostearate biliquid foam 3.5                                   90% Dimethiconol biliquid foam 1.5                                            Glycerine 2.5                                                                 Methyldibromoglutaronitrile in phenoxyethanol (preservative) 0.1                                          100.0                                           ______________________________________                                    

The `Carbopol` was dispersed in water using a high-shear rotorstatormixer (Silverson) and aqueous 1% sodium hydroxide solution was addeduntil a clear viscous gel with pH 7 was obtained. The `Natrosol` wassimilarly dispersed but without the need of sodium hydroxide. All thebiliquid foams were prepared as described in Example 1 using mineraloil, cyclomethicone, isopropyl isostearate or dimethiconol asappropriate. All the ingredients were mixed together at room temperatureuntil a smooth, semiviscous white gel was obtained. When applied to theskin the gel spread easily in a light and refreshing manner, was rapidlyabsorbed without stickiness and produced a smooth moisturised feeling.

EXAMPLE 5

A Toner

The total composition of the toner is:

    ______________________________________                                                                  %                                                   ______________________________________                                        Water                       79.9                                                1% Aqueous `Carbopol` 980 (neutralised with 8.0                               sodium hydroxide)                                                             90% Cyclomethicone biliquid foam 6.0                                          90% Dimethiconol biliquid foam 1.0                                            Glycerine 5.0                                                                 Methyldibromoglutaronitrile in phenoxyethanol (preservative) 0.1                                          100.0                                           ______________________________________                                    

The ingredients were prepared as described in Example 4 and mixedtogether at room temperature until a uniform slightly cloudy liquid wasobtained. When applied to the skin the liquid produced a light,non-greasy refreshing sensation leaving the skin feeling smooth.

EXAMPLE 6

A Moisturising Shower Gel

The total composition of the gel is as follows:

    ______________________________________                                                                  %                                                   ______________________________________                                        Water                       38.88                                               28% Aqueous sodium lauryl ether sulphate 32.14                                30% aqueous coamidopropylbetaine 12.38                                        Lauryl glucoside 2.25                                                         90% Dimethicone biliquid foam 3.50                                            Polyethylene glycol (PEG-18) glyceryl oleate/cocoate 0.15                     Glycol stearate 0.30                                                          Ethoxylated stearyl alcohol 0.30                                              (Steareth-4)                                                                  1% Aqueous `Carbopol` 980 (neutralised with 10.00                             sodium hydroxide)                                                             Methyldibromoglutaronitrile in phenoxyethanol (preservative) 0.10                                         100.00                                          ______________________________________                                    

The `Carbopol` and biliquid foams were prepared as described in previousexamples and the ingredients were mixed together as described in Example3 until a viscous shower gel having a slightly pearly appearance wasobtained. This was cooled to room temperature. When used as a shower gelit gave the skin a pleasant emollient effect during use and after theskin was dried it had a clean, smooth and moisturised feel.

What is claimed is:
 1. A stable dispersion comprising an oil-basedbiliquid foam and an aqueous gel, wherein the oil-based biliquid foamconstitutes from 1 to 80% by weight of the dispersion, the aqueous gelconstitutes frolic 20 to 99% by weight of the dispersion, and saiddispersion also includes a surfactant.
 2. A dispersion as claimed inclaim 1 wherein the biliquid foam comprises from 1 to 50% by weight ofthe dispersion and the aqueous gel comprises from 50 to 99% by weight ofthe dispersion.
 3. A dispersion as claimed in claim 1 wherein thesurfactant comprises from 0.05 to 0.5% by weight thereof.
 4. Adispersion as claimed in claim 3 wherein the surfactant comprises from0.05 to 0.3% by weight thereof.
 5. A dispersion as claimed in claim 1which comprises as the aqueous gel an aqueous fluid which contains oneor more components selected from the group consisting of a primarysurfactant, a coactive surfactant, a coactive viscosity modifier and agelling agent.
 6. A dispersion as claimed in claim 5 wherein thebiliquid foam comprises from 1 to 10% by weight of the dispersion.
 7. Adispersion as claimed in claim 6 wherein the biliquid foam comprisesfrom 2 to 5% by weight of the dispersion.
 8. A method for themanufacture of a stabilised dispersion as claimed in claim 1 whichcomprises incorporating an oil-based biliquid foam into an aqueous gel.